[Plugin: WP Super Cache] You do not have sufficient permissions to access this page (4 posts)

I had wp-supercache working perfectly in the 2.7 WP version, now it's not working. When I try to clear cache, or enable/disable the cache, I get "You do not have sufficient permissions to access this page.". I disabled and removed the plugin and reinstalled it to see if that would work, same error!

I'm logged in as admin (the only user). I can't figure out what's going on!

I installed a new WP install in a subfolder, and immediately installed super cache and SAME ERROR!